KR102179976B1 - Method for manufacturing molten iron - Google Patents

Abstract

A method for manufacturing molten iron according to an embodiment of the present invention includes the steps of introducing an iron source and carbonaceous material to the top of the molten iron furnace; Including the step of blowing the silicon-containing by-products through the windpipe of the furnace and discharging the molten iron and slag from the furnace.

Description

Molten iron manufacturing method {METHOD FOR MANUFACTURING MOLTEN IRON}

It relates to a method for manufacturing molten iron. Specifically, it relates to a method for producing molten iron for producing molten iron containing high silicon content.

Steel processing is one of the industries with high carbon dioxide emissions. One of the ways to reduce carbon dioxide emissions is a method of producing molten steel by mixing a large amount of scrap during molten iron. If scrap is used, the crude steel production increases, while the carbon fuel used does not increase, reducing carbon dioxide emissions. If a large amount of scrap is mixed during the chartering, a problem occurs in that the temperature of the charter is lowered. To this end, temporary regulation is added to the molten iron to increase the silicon concentration, and oxygen is blown to increase the temperature of the molten iron by exothermic reaction to mix the scrap.

Conventional techniques aimed at lowering the silicon content in molten iron (melting iron). In order to manufacture high-clean steel, technology was developed to produce molten iron by lowering the silicon content.

As a method for producing low silicon content molten iron, the silicon content in the molten metal was lowered by lowering the combustion zone gas temperature and promoting the desiliconization reaction of titanium by blowing titanium-containing iron ore through a windpipe. In addition, the concentration of sulfur in the molten iron was controlled to suppress the adsorption of silicon in the molten iron, thereby lowering the silicon content in the molten iron. As such, conventional techniques have only proposed methods for lowering the silicon content in molten iron.

However, in recent years, it is necessary to use a large amount of scrap in order to reduce carbon dioxide emission, and accordingly, attempts to increase the silicon content in the molten iron are being made.

As described above, various techniques for lowering the silicon content in blast furnace molten iron have been proposed, but a technique for increasing the silicon content in molten iron has not yet been proposed.

It provides a method for manufacturing molten iron. Specifically, it provides a molten iron manufacturing method for manufacturing a high silicon content molten iron.

A method for manufacturing molten iron according to an embodiment of the present invention includes the steps of introducing an iron source and carbonaceous material to the top of the molten iron furnace; Including the step of blowing the silicon-containing by-products through the windpipe of the furnace and discharging the molten iron and slag from the furnace.

The silicon-containing by-product may contain at least 20% by weight of SiO ₂ .

The silicon-containing by-product may further include Al ₂ O ₃ : 10 to 25 wt%, CaO: 0.1 to 5 wt%, and MgO: 0.1 to 5 wt%.

The silicon-containing by-product may have a basicity of 1.2 or less represented by Equation 1 below.

[Equation 1]

[C/S]=[CaO]/[SiO ₂ ]

(In Equation 1, [C/S] represents the basicity of the silicon-containing by-product. [CaO] and [SiO ₂ ] represent the content (% by weight) of CaO and SiO _{2 in} the silicon-containing by-product.)

The silicon-containing by-product may satisfy Equation 2 below.

[Equation 2]

[SiO ₂ ]/[MgO] ≥ 169×[C/S] ⁵ -510×[C/S] ⁴ + 587×[C/S] ³ -315×[C/S] ² +78.6×[C/ S]-6

(In Equation 2, [C/S] represents the basicity of the silicon-containing by-product. [MgO], [CaO] and [SiO ₂ ] represent the content (% by weight) of MgO, CaO, and SiO _{2 in} the silicon-containing by-product. .)

The silicon-containing by-product can be blown in from 5 to 100 kg/ton of molten iron.

The slag may contain up to 16% by weight of Al ₂ O ₃ .

The slag may further include SiO ₂ and CaO, and a basicity (C/S) represented by the following formula 3 may be 1.2 or less.

[Equation 3]

[C/S]=[CaO]/[SiO ₂ ]

(In Equation 3, [C/S] represents the basicity of the slag. [CaO] and [SiO ₂ ] represent the contents (% by weight) of CaO and SiO _{2 in} the slag.)

The molten iron may have a Si content of 0.6% by weight or more.

According to one embodiment of the present invention, it is possible to manufacture molten iron having an increased Si content without negatively affecting the old sulfur.

1 is an experiment result in Example 3.

Terms such as first, second and third are used to describe various parts, components, regions, layers, and/or sections, but are not limited thereto. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is for referring only to specific embodiments and is not intended to limit the present invention. Singular forms as used herein also include plural forms unless the phrases clearly indicate the opposite. The meaning of “comprising” as used in the specification specifies a specific characteristic, region, integer, step, action, element and/or component, and the presence of another characteristic, region, integer, step, action, element and/or component, or It does not exclude additions.

When a part is referred to as being "on" or "on" another part, it may be directly on or on another part, or other parts may be involved in between. In contrast, when a part is referred to as being “directly above” another part, no other part is intervened.

Although not defined differently, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms defined in a commonly used dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal meaning unless defined.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

A method for manufacturing molten iron according to an embodiment of the present invention includes the steps of inputting an iron source and carbonaceous material to the top of the molten iron furnace (S10); Including a step (S20) of injecting silicon-containing by-products through a windpipe of the molten iron furnace and a step (S30) of discharging molten iron and slag from the molten iron furnace.

Hereinafter, each step will be described in detail. Each step is described irrespective of the time before and after, and each step may be performed sequentially or simultaneously.

First, in step S10, the iron source and carbonaceous material are put into the top of the furnace.

In an embodiment of the present invention, the furnace used in the method for manufacturing molten iron may be used without limitation. Specifically, a blast furnace, FINEX ^® or Corex ^® may include a melting gasification furnace 60 of a process, a melting gasification furnace of a process.

In the FINEX ^® PROCESS, powdered iron ore is charged into a multi-stage fluidized reduction furnace, and then flow-reduced sequentially in the reduction furnace, and then the discharged reduced iron is charged into the melting gasifier along with coal, and oxygen is supplied through a fan at the bottom of the furnace. It refers to the process of manufacturing molten iron by blowing.

The iron source is not particularly limited, and may include iron ore, sintered ore, or reduced iron. The carbonaceous material is also not particularly limited, and may include coke and coal briquettes formed from powdered coal.

The iron source and carbonaceous material injected into the furnace top in the molten iron furnace melt and reduce the iron source using carbonaceous material as a reducing material and fuel to produce molten iron.

Next, in step (S20), silicon-containing by-products are blown through the windpipe of the molten iron furnace. High-temperature air or oxygen is blown into the furnace of the melting furnace to provide oxygen for an exothermic reaction. In addition to air or oxygen, coal or powdered iron may additionally be blown.

In an embodiment of the present invention, the silicon-containing by-product may include a by-product in a molten iron manufacturing process containing a large amount of silicon. For example, fly ash, which is a by-product collected from exhaust gas of a power plant, may be used. Fly ash contains a large amount of Si and is suitable for use as an embodiment of the present invention. In addition to fly ash, various by-products including Si can be used.

The silicon-containing by-product may contain at least 20% by weight of SiO ₂ . When the SiO ₂ content is included too little, it is difficult to increase the Si content in molten iron. More specifically, the silicon-containing by-product may include 20 to 70% by weight of SiO ₂ . More specifically, the silicon-containing by-product may include 30 to 60% by weight of SiO ₂ .

The silicon-containing by-product may further include Al ₂ O ₃ : 10 to 25 wt%, CaO: 0.1 to 5 wt%, and MgO: 0.1 to 5 wt%. When too much Al ₂ O ₃ is included, the Al ₂ O ₃ content in the slag increases due to the blowing of silicon-containing by-products, and in this case, the slag viscosity increases, so that liquid permeability may be a problem at the bottom of the furnace. When too much MgO and CaO are included, the content of MgO and CaO in the slag increases due to the blowing of silicon-containing by-products, and in this case, a problem that the Si content in the molten iron does not increase even if the amount of blowing is increased may occur. More specifically, the silicon-containing by-product may further include Al ₂ O ₃ : 13 to 23 wt%, CaO: 1 to 5 wt%, and MgO: 1 to 3 wt%.

Silicon-containing by-products include SiO ₂ and CaO, and the basicity represented by the following formula 1 may be 1.2 or less.

[Equation 1]

[C/S]=[CaO]/[SiO ₂ ]

(In Equation 1, [C/S] represents the basicity of the silicon-containing by-product. [CaO] and [SiO ₂ ] represent the content (% by weight) of CaO and SiO _{2 in} the silicon-containing by-product.)

If the basicity of the silicon-containing by-product is too high, it may adversely affect the operation of the molten iron, and the silicon concentration in the molten iron may decrease. More specifically, the basicity of the silicon-containing by-product may be 0.01 to 1.2. More specifically, the basicity of the silicon-containing by-product may be 0.05 to 1.2.

In addition, the silicon-containing by-product may satisfy Equation 2 below.

[Equation 2]

[SiO ₂ ]/[MgO] ≥ 169×[C/S] ⁵ -510×[C/S] ⁴ + 587×[C/S] ³ -315×[C/S] ² +78.6×[C/ S]-6

When Equation 2 is satisfied, the silicon content in the molten iron may be increased through the injection of silicon-containing by-products.

The silicon-containing by-product can be blown in from 5 to 100 kg/ton of molten iron. When too little silicon-containing by-products are blown, it may be difficult to properly obtain the desired Si content in molten iron. If too much silicon-containing by-products are blown, the combustion temperature decreases rapidly, and stable operation may be difficult. More specifically, 5 to 50 kg/ton of silicon-containing by-products may be injected. More specifically 10 to 25kg / molten iron-ton can be blown. The kilogram/ton of molten iron means a silicon-containing by-product (kg) that is blown per molten iron (ton).

Next, in step S30, molten iron and slag are discharged from the molten iron furnace.

As the injection amount of silicon-containing by-products increases, the concentration of MgO in the slag decreases and the base also decreases. For this reason, the content of silicon in the molten iron gradually increases. However, as the injection amount of silicon-containing by-products increases, Al ₂ O ₃ in the slag increases and the basicity decreases, which may deteriorate the fluidity of the slag and lower the liquid permeability in the molten iron furnace. Also, the amount of slag generated may increase.

Specifically, the slag may contain Al ₂ O ₃ in an amount of 16% by weight or less. If too much Al ₂ O ₃ is included, the fluidity of the slag may be deteriorated and the liquid permeability in the molten iron furnace may be lowered. More specifically, the slag may contain 10 to 16% by weight of Al ₂ O ₃ .

The slag may further include SiO ₂ and CaO, and a basicity (C/S) represented by the following formula 3 may be 1.2 or less.

[Equation 3]

[C/S]=[CaO]/[SiO ₂ ]

(In Equation 3, [C/S] represents the basicity of the slag. [CaO] and [SiO ₂ ] represent the contents (% by weight) of CaO and SiO _{2 in} the slag.)

Increasing the basicity may adversely affect the operation of the molten iron, and the silicon concentration in the molten iron may decrease.

According to the above-described configuration, in an embodiment of the present invention, the silicon content in molten iron can be increased. Specifically, the molten iron may have a Si content of 0.6% by weight or more. More specifically, the molten iron may have a Si content of 0.64% by weight or more. More specifically, the molten iron may have a Si content of 0.64 to 0.7% by weight.

Hereinafter, specific examples of the present invention will be described. However, the following examples are only specific examples of the present invention, and the present invention is not limited to the following examples.

Example 1: Si content in molten iron according to change in injection amount

The experiment was conducted by varying the amount of fly ash containing the components of Table 1 to the windpipe of the blast furnace for discharging the slag containing the components of Table 1. The slag component, the amount of slag generated, and the Si content in molten iron are summarized in Table 2 below.

(weight%) Al ₂ O ₃ CaO MgO SiO ₂ Other Basicity (C/S) Blast furnace slag 14.78 42.04 3.82 35.3 4.06 1.19 Fly ash 20.51 3.44 1.5 56.52 18.03 0.06

Blown quantity
(kg/melted iron-ton) Al ₂ O ₃
(weight%) CaO (% by weight) MgO
(weight%) SiO ₂
(weight%) basicity
(C/S) Slag generation amount
(kg/melted iron-ton) Si content in molten iron
(weight%) 5 14.87 41.42 3.78 35.64 1.16 313.20 0.68 10 14.96 40.83 3.75 35.97 1.14 318.20 0.74 15 15.05 40.25 3.71 36.28 1.11 323.20 0.79 20 15.13 39.69 3.68 36.59 1.08 328.20 0.83 25 15.21 39.14 3.65 36.89 1.06 333.20 0.88

As shown in Table 2, it can be seen that the Si content in the molten iron increases as the injection amount increases within the proper basicity range.

Example 2: SiO ₂ Si content in molten iron according to /MgO

Among the components of silicon-containing by-products blown into the blast furnace, the basicity was fixed to 1, and the ratio and amount of SiO ₂ and MgO were varied as shown in Table 3 below.

The Si content in molten iron is summarized in Table 3 below.

SiO ₂ /MgO Blowing amount (kg/melted iron-ton) 0 10 20 30 40 50 2 0.63 0.62 0.61 0.60 0.59 0.58 3 0.63 0.63 0.62 0.62 0.62 0.62 3.5 0.63 0.63 0.63 0.63 0.63 0.63 4 0.63 0.63 0.63 0.64 0.64 0.64 6 0.63 0.64 0.65 0.65 0.66 0.66 8 0.63 0.64 0.65 0.66 0.67 0.68 10 0.63 0.64 0.65 0.66 0.67 0.68

As shown in Table 3, when the SiO ₂ /MgO value of the silicon-containing by-product is 3.5 or less, it can be seen that the content of Si in the molten iron does not increase even if the injection amount increases.

Example 3: SiO ₂ Relationship between /MgO and basicity

When a silicon-containing by-product of 50 kg/ton of molten iron is blown, the minimum SiO ₂ /MgO when the Si content in the molten iron increases is shown in FIG. 1.

As shown in FIG. 1, it can be seen that as the basicity increases, the SiO ₂ /MgO value for increasing the Si content in molten iron increases rapidly.

In addition, it can be confirmed that the Si content in the molten iron can be increased by injecting silicon-containing by-products only when Equation 2 is satisfied.

The present invention is not limited to the embodiments, but may be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present invention pertains may use other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that it can be implemented. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting.

Claims (8)

Injecting iron source and carbonaceous material to the top of the furnace;
Injecting a silicon-containing by-product through a windpipe of the molten iron furnace, and
Including the step of discharging molten iron and slag from the molten iron furnace,
The silicon-containing by-products include SiO ₂ : 20 wt% or more, Al ₂ O ₃ : 10 to 25 wt%, CaO: 0.1 to 5 wt% and MgO: 0.1 to 5 wt%,
The basicity (C/S) represented by the following formula 1 is 1.2 or less,
Satisfies Equation 2 below,
The slag contains Al ₂ O ₃ in an amount of 16% by weight or less,
The molten iron is a method of manufacturing molten iron having a Si content of 0.6% by weight or more.
[Equation 1]
[C/S]=[CaO]/[SiO ₂ ]
[Equation 2]
[SiO ₂ ]/[MgO] ≥ 169×[C/S] ⁵ -510×[C/S] ⁴ + 587×[C/S] ³ -315×[C/S] ² +78.6×[C/ S]-6
(In Equations 1 and 2, [C/S] represents the basicity of the silicon-containing by-product. [MgO], [CaO], and [SiO ₂ ] are the contents of MgO, CaO and SiO _{2 in} the silicon-containing by-product (% by weight ).) delete delete delete delete The method of claim 1,
Molten iron manufacturing method for blowing the silicon-containing by-products from 5 to 100kg/ton of molten iron. delete delete

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